Author

Publication Date

Date of Final Oral Examination (Defense)

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Kinesiology

Department

Kinesiology

Major Advisor

Scott A. Conger, Ph.D.

Advisor

Matthew Darnell, Ph.D.

Advisor

Philip Ford, Ph.D.

Abstract

Introduction: Dietary nitrate (NO3-) can serve as a substrate for the important signaling molecule nitric oxide (NO). Recent studies suggest that NO3- beet juice could be beneficial during anaerobic (i.e. short duration, high power) exercise, though this area has received much less attention than beet juice’s effects during aerobic exercise. Purpose: The purpose of this study was to determine if acute dietary NO3- supplementation, in the form of beet juice, could improve measures of anaerobic power in trained, healthy men during a primarily anaerobic bout of exercise. A secondary purpose was to investigate if NO3- supplementation produced a greater increase in performance measures in a 60-second (60-s) bout of exercise compared to a 30-second (30-s) bout. Methods: Fourteen male hockey players participated in this study. The study used a cross-over, double-blind design. The exercise protocol included maximal effort 30-s and 60-s tests on a stationary bike, with a fixed amount of resistance applied. In addition to two familiarization trials, a 30-s placebo trial, 30-s beet juice trial, 60-s placebo trial, and 60-s beet juice trial were completed by each participant in random order, over six total visits. The beet juice supplement (RediBeets, The AIM Companies, Nampa, ID) contained ~8mmol/496 mg of dietary NO3-. Apple-cherry-cranberry juice served as the placebo, containing a negligible amount of NO3. Paired t-tests were run to compare performance in both the 30-s and 60-s trials, analyzing peak and mean power (W), peak and mean RPM, relative power (W/kg), total work (J), and fatigue index (FI, %). Results: No statistical differences were found between the beet juice and placebo trials for the 30 or 60-s tests. The percent change (∆) for FI was significantly different between the 30 and 60-s tests. The FI decreased between the P30 and B30 (suggesting less fatigue occurred after beet supplementation) while it increased between the P60 and B60 (suggesting less fatigue occurred after placebo supplementation), accounting for the statistical significance when comparing the percent change (∆) during the 30-s test to the change during the 60-s test. No other significant differences emerged when comparing the percent change between the 30 and 60-s tests. Conclusion: A dose of ~8 mmol of beet juice did not improve anaerobic exercise performance during a 30 and 60-s all out cycling sprint. Performance during the 60-s bout was not impacted to a greater extent than the 30-s bout after beet juice supplementation. Beet juice supplementation during high power, anaerobic exercise does not produce similar improvements in performance that have been reported during aerobic exercise.